Identification of an idiotypic marker of a major regulatory T cell of the immune response in B10.BR mice to ferredoxin. The relationship of idiotypic regulation to conventional hapten-carrier effects

Modulation of immune response to Lol p I by pretreatment with anti-idiotypic antibody is not restricted to the idiotypic expression

To study the role of anti-idiotypic antibodies in the regulation of the immune response to Lol p I (the major allergenic component of rye grass pollen), we have recently generated a panel of three MoAbs directed against distinct epitopes of Lolp I and an anti-idiotypic MoAb directed against the idiotype borne by one of the anti-Lol p I MoAbs (290A-167). The effects of pretreatment with this anti-idiotypic MoAb in BALB/c mice before immunization with the antigen have been examined. The anti-idiotypic MoAb or unrelated MoAb were given weekly for 8 weeks intraperitoneally. Mice then received the antigen (2 micrograms) adsorbed with alum (2 mg) at weeks 9, 11 and 13. Serum anti-Lol p I antibodies (IgG or IgE) and specific idiotypic responses were measured. Anti-Lol p I IgG antibodies could be detected before immunization with Lol p I only in mice pretreated with anti-idiotypic MoAb. Immunization with Lol p I induced an anti-Lol p I IgG response in both groups, but this response was higher in mice that received anti-idiotypic MoAb. Similar profiles were seen for specific IgE antibodies and idiotypic responses. Surprisingly, idiotypes borne by other anti-Lol p I MoAbs (539A-6 and 348A-6) had also been enhanced after pretreatment with the anti-290A-167 MoAb. These observations suggested that the pretreatment with this anti-idiotypic MoAb modulates not only the expression of the respective idiotype, but also affects other idiotype responses.

Selective activation of immunoregulatory T-cell circuits by an Ia+ antigen-presenting cell line

ORA I-a, a cloned Ia+ monocyte tumor line, interacts with distinct immunoregulatory T-cell subsets. ORA cells present soluble and alloantigen to primed lymph node T cells and alloantigen to antigen-activated T-cell clones. However, they induce dose-dependent suppression during primary mixed lymphocyte cultures. Activation of a mixed lymphocyte response (MLR) suppressor pathway is mediated by Ly 1+ T cells. This T-cell subset proliferates in response to ORA when Ly 2+ cells are depleted. Furthermore, once activated, Ly 1+ T cells induce effectors of suppression within fresh T-cell populations. These studies indicate that antigen presentation to distinct T-cell subsets during different stages of an immune response may be mediated by unique antigen-presenting cell subpopulations. Immune homeostasis may thus be controlled not only by regulatory T cells, but also by unique antigen-presenting cells which are responsible for their selective activation.

Abrogation and reconstitution of nonresponsiveness: a correlation with high network connectivity

A monoclonal antibody (Fd-B2) to ferredoxin, which bears an idiotype scarcely expressed in any of a wide variety of mouse strains, is able to markedly enhance the response to ferredoxin of both high-responder and intermediate-responder strains. A rabbit anti-idiotype serum to Fd-B2 also specifically enhances the response to ferredoxin in such mice. Most remarkably, the treatment of nonresponder T cells by either the idiotype (Fd-B2) plus complement or anti-idiotype antiserum plus complement causes them to be responsive in adoptive transfer experiments. The two responding populations (idiotype-treated and anti-idiotype-treated) can then be combined to reconstitute the nonresponsive state. When the nonresponders are treated with either Fd-B2 idiotype plus complement or anti-idiotype plus complement and subsequently respond, the idiotype of the anti-ferredoxin antibody produced does not bear the Fd-B2 idiotype. We interpret the results as being consistent with a model in which the unresponsive state for ferredoxin is a state of high network connectivity of the ferredoxin-specific T cells.

An appraisal of survival strategies

Only a few years ago parasite immunology looked an unattractive subject better left to the dogged specialists. Parasites and hosts had been playing chess together for a million years, and there seemed little prospect of perturbing matters in favour of the host immune system. All that has changed, for three reasons. Firstly, we have learned how to grow at least some parasites in vitro, and prospects of doing so with others are encouraging. Secondly, progress in cellular immunology has revealed the sort of loopholes in the host defence system which parasites are likely to exploit: we are learning the questions which matter about parasites as antigens. Thirdly, and most importantly, molecular genetics is being brought to bear on parasites: we can now see a real, though long-term, prospect of manufacturing practicable vaccines through bio-engineering, and more immediately it gives us the tools needed to probe the host immune responses in the form of cloned antigens.

Evidence for the presence of idiotype-bearing regulatory T cells in which idiotype expression does not show linkage to either IgH alleles or the MHC

An anti-idiotypic antiserum was raised in rabbits to a monoclonal antibody with specificity for one of the two antigenic determinants on the ferredoxin (Fd) molecule. The monoclonal antibody (Fd-B2) was derived from fusion of spleen cells from Fd-immune B10.BR (H-2k, Ighb). Examination of an extensive number of samples of Fd-immune serum from B10.BR and other mouse strains established that the Fd-B2 idiotype is essentially never present in such sera in detectable concentrations (greater than 30 ng/ml). Administration of the anti-idiotypic antibody (anti-Fd-B2) i.v. to B10.BR mice, or treatment of B10.BR T cell-enriched populations with anti-Fd-B2 + C prior to adoptive transfer to irradiated B10.BR recipients followed by challenge with Fd resulted in a significant increase in the production of anti-Fd antibodies. This effect was specific and was not reflected by a change in expression of the Fd-B2 idiotype in the antibody produced. Similarly, injection of 10 micrograms of Fd-B2 into B10.BR mice resulted in an enhanced anti-Fd response. When similar experiments were carried out using B10.D2 mice (H-2d, Ighb), which are genetic non-responders to Fd, it was observed that treatment which anti-Fd-B2 followed by challenge with Fd resulted in production in treated animals of significant levels of antibody to Fd. Again, the antisera thus produced did not contain detectable levels of the Fd-B2 idiotype. Further experiments using high responder (H-2k) mice with Igh allotypes differing from the B10 strains (C57/BR, Igha, and RF/J, Ighc), showed that treatment of these animals with anti-Fd-B2 also resulted in a highly significant enhancement of the anti-Fd response. These data imply that the anti-idiotypic antiserum (anti-Fd-2B) is exerting its influence by acting on an id + population of T cells and that the expression of this id is not dependent on genetic linkage to either the H-2 or the Igh loci.

Immunoregulation of the anti-bovine serum albumin response by polyclonal and monoclonal antibodies

Monoclonal or polyclonal antibodies directed toward determinants on limited structures of bovine serum albumin (BSA) (P505-582) were shown to regulate the entire anti-bovine serum albumin (BSA) immune response when passively administered to mice 24 hr prior to immunization. Regulation was observed as suppression of the humoral IgG immune response toward all BSA determinants except those on fragment P505-582. By Day 21 suppression of humoral response was most pronounced toward determinants present on the carboxy terminal end of the molecule (N 307-582). These observations demonstrate that monoclonal antibodies directed against a single determinant on a protein molecule have the capacity to regulate the immune response to a multiplicity of determinants present on the same protein. The data lend support to concepts of antibody-induced regulation by induction of suppressor cells or idiotype recognition.